The present invention relates generally to power tools, and more particularly to air compressors.
Air compressors are becoming commonplace in home workshops. In general, an air compressor, or an air pump, is a machine that decreases the volume and increases the pressure of a quantity of air by mechanical means. Air thus compressed possesses great potential energy, because when the external pressure is removed, the air expands rapidly. The controlled expansive force of compressed air is used in many ways and provides the motive force for air motors and tools, including pneumatic hammers, air drills, sandblasting machines, and paint sprayers.
A conventional home workshop air compressor includes a storage compressor tank for compressed air, and a prime mover mounted on the storage compressor tank for compressing the air in the compressor tank. The prime mover may be a gas engine or an electric motor, but most conventional home workshop models utilize electric power. The compressor tanks are typically steel and cylindrical in shape, and sizes vary greatly, but typically, home workshop models range between four and thirty gallons. An air compressor typically includes a pedestal of some kind (e.g., four feet) that allows the compressor to rest on a surface such as a floor. Alternatively, for some larger models, a pair of wheels may be provided on one end of the compressor tank and a handle on the other end, permitting the air compressor to be wheeled around a work shop, for example.
During the compression process in an air compressor, ambient air, which includes atmospheric humidity (i.e., water vapor), is drawn into the compressed air system where it is compressed to a desired discharge pressure. During the compression process, the water vapor is heated, and while stored in the compressor tank, the air and water vapor cool. Condensation is the moisture that drops out of the airflow as it cools. This condensation forms water in the bottom of the compressor tank, often called condensate. Condensate in an air compressor tank can cause many problems, such as rust and scale in the compressor tank, or water backup in the prime mover.
Most home workshop air compressors include a drain at a lower portion of the compressor tank to drain condensate out of the compressor tank. Although the condensate drains work well for their intended purpose, users often find the drains hard to access, because a user must stoop down and reach underneath the air compressor to release the drain. In addition, to fully drain the condensate, the user may have to hold the drain open for several seconds or longer to drain all condensate from the compressor tank. This process may be uncomfortable because of the inconvenient location of the drain. Moreover, the flow of condensate from the drain may be messy, because the condensate may disperse as a broad spray because of the configuration of the drain and the pressure in the compressor tank.
The present invention provides a foot-actuated condensate drain for an air compressor tank. In accordance with one aspect of the present invention, the foot-actuated condensate drain includes a lever that is connected to a valve on the bottom of the air compressor tank. Movement of the lever, for example by a user""s foot, causes the drain valve to open.
In accordance with another aspect of the present invention, the lever may be moved to a catch position where the drain valve is held in an open position, even if the user releases his or her foot. In this manner, a user may step on the lever and slide it or move it into the catch position, thereby allowing the valve to continue draining even if the user removes his or her foot from the lever. The catch may be provided, for example, by a slot into which the lever may be moved sidewise, but which restricts movement of the lever in the direction (e.g., upwards) that closes the valve.
In accordance with a further aspect of the present invention, the valve is constructed so that condensate may flow out of the valve in an orderly, directed flow, for example in a thin stream straight downward. To this end, the valve includes a valve stem situated within a valve body. The valve stem is hollow and includes a seal for closing off the opening, and radial holes below the seal and in fluid communication with the hollow interior portion of the stem. A spring biases the valve stem into the closed position. When moved away from the closed position, fluid in the compressor tank flows out of the opening, around the seal, into the radial holes, through the stem, and out of the valve. The flow out of the stem is much more focused than the flow out of prior art drains or valves.
In accordance with one aspect of the present invention, the lever is attached to the stem, and downward movement of the lever causes a corresponding downward movement of the stem. To this end, the lever includes an extension that is situated opposite an actuation end of the lever and on an opposite side of the valve than the actuation end. The extension engages a surface near the bottom of the compressor tank and rotation of the lever occurs around this point of engagement. This arrangement allows the extension to act as a fulcrum, whereby leverage may be used to open the valve.
Other advantages will become apparent from the following detailed description when taken in conjunction with the drawings, in which: